From Li₂NiO₃ to high-performance LiNiO₂ cathodes for application in Li-ion and all-solid-state batteries

The synthesis of LiNiO₂ (LNO) typically involves oxidizing Ni(II) to Ni(III), thus leading to Ni_Li point-defect formation. Here, materials containing Ni(IV) in the form of overlithiated Li₁₊Ni_1-O₂ (0 ≤ x ≤ 1/3) are converted into LNO. This method produces low defect-density samples at high temperatures, offering an attractive route toward coarse-grained particles that are naturally coated by the byproduct Li₂O. In thiophosphate-based solid-state batteries, this kind of self-coating effect shows a direct correlation between residual lithium content and cycling performance.